mikew@wyse.wyse.com (Mike Wexler) (02/09/89)
Submitted-by: bradley@dsl.cis.upenn.edu (John Bradley)
Posting-number: Volume 3, Issue 11
Archive-name: xcmap/patch1
This corrects two bugs in xcmap. The first bug had to do with X Servers that
didn't return a power of 2 on the function "XDisplayCells()". The program
wouldn't run on them. The second bug occurred when you dragged the mouse
outside of the window. It would return out-of-value pixels, and eventually
crash.
diff -c xcmap/README xcmapnew/README
*** xcmap/README Wed Feb 8 17:25:35 1989
--- xcmapnew/README Wed Feb 8 17:10:10 1989
***************
*** 1,3 ****
--- 1,47 ----
xcmap is a program that displays the contents of the default colormap on
4-, 6-, and 8-bit X11 displays. It displays the colormap both as a grid of
colored rectangles, and as RGB components.
+
+ This is a very useful thing to anybody who's trying to do color-intensive
+ programs (such as displaying GIF pictures...) on X.
+
+ It's also kind of neat to watch.
+
+ John Bradley - bradley@cis.upenn.edu
+
+
+ PATCH 1:
+ Contributed by Dave Gorgen / Apollo Computer Inc (dpg@citi.umich.edu)
+ Allows xcmap to run on X servers that pre-allocate colors for the cursor,
+ returning an "XDisplayCells()" value != a power of 2. This would include
+ Apollos, DEC QDSSs, and no doubt some other machines.
+
+ -------------
+ (The full description of the problem, from Dave's letter...)
+ I was happy to see xcmap posted on comp.sources.x; it's one of those
+ programs I always meant to write but never got around to.
+
+ However, when I ran it on my Apollo server I got:
+
+ xcmap: dispcells = 254. This program can only deal with 4, 6, and 8-bit display
+ s.
+
+ The problem is that xcmap, like many color X clients, incorrectly assumes
+ that if a visual is n bits deep, it must support exactly 2**n colormap entries.
+ The protocol explicitly allows fewer entries; this fact is used by several X
+ servers (Apollo color servers, DEC QDSS servers, and perhaps others) to reserve
+ 2 slots for the cursor colors. Unless the display hardware has a 2-color cursor
+ sprite, this is the only correct way to do a color cursor that I know of.
+
+ (The Sun color cursor support on the MIT tape, which allocates the cursor
+ colors dynamically out of the default color map, is acknowledged by the author(s
+ )
+ to be wrong. I don't know how IBM, HP or MacII color displays do cursors.)
+
+ Anyway, I modified xcmap to accept any value it finds for dispcells <= 256.
+ It will draw the same square array of pixels, including the out-of-bounds ones,
+ but if you select an out-of-bounds pixel to display its RGB values, it will
+ just say that the pixel is out-of-bounds. For what it's worth, this also allows
+ xcmap to run on monochrome displays, albeit rather boringly.
+ ------------------
+
diff -c xcmap/patchlevel.h xcmapnew/patchlevel.h
*** xcmap/patchlevel.h Wed Feb 8 17:25:38 1989
--- xcmapnew/patchlevel.h Wed Feb 8 17:02:59 1989
***************
*** 1 ****
! #define PATCHLEVEL 0
--- 1 ----
! #define PATCHLEVEL 1
diff -c xcmap/xcmap.c xcmapnew/xcmap.c
*** xcmap/xcmap.c Wed Feb 8 17:25:38 1989
--- xcmapnew/xcmap.c Wed Feb 8 17:15:12 1989
***************
*** 106,123 ****
theVisual = DefaultVisual(theDisp,theScreen);
dispcells = DisplayCells(theDisp, theScreen);
! if (dispcells!=16 && dispcells!=64 && dispcells != 256) {
! sprintf(tmpstr,"dispcells = %d. This program can only deal with 4, 6, and 8-bit displays.",dispcells);
FatalError(tmpstr);
}
- switch (dispcells) {
- case 16: nxcells = nycells = 4; break;
- case 64: nxcells = nycells = 8; break;
- case 256: nxcells = nycells = 16; break;
- }
-
-
/**************** Create/Open X Resources ***************/
if ((mfinfo = XLoadQueryFont(theDisp,FONT))==NULL) {
sprintf(tmpstr,"couldn't open '%s' font",FONT);
--- 106,125 ----
theVisual = DefaultVisual(theDisp,theScreen);
dispcells = DisplayCells(theDisp, theScreen);
!
! if (dispcells>256) {
! sprintf(tmpstr,"dispcells = %d. This program can only deal with <= 8-bit displays.",dispcells);
FatalError(tmpstr);
}
+ else if (dispcells>64)
+ nxcells = nycells = 16;
+ else if (dispcells>16)
+ nxcells = nycells = 8;
+ else if (dispcells>4)
+ nxcells = nycells = 4;
+ else
+ nxcells = nycells = 2;
/**************** Create/Open X Resources ***************/
if ((mfinfo = XLoadQueryFont(theDisp,FONT))==NULL) {
sprintf(tmpstr,"couldn't open '%s' font",FONT);
***************
*** 339,344 ****
--- 341,349 ----
static unsigned long pix, lastpix;
static int pvaly;
+ if (x<0) x=0; if (x>=WIDE) x=WIDE-1;
+ if (y<0) y=0; if (y>=HIGH) y=HIGH-1;
+
if (!pvalup) { /* it's not up. make it so */
if (y >= HIGH/2) pvaly = 0; else pvaly = HIGH - 12;
pvalup = 1;
***************
*** 356,368 ****
XSetForeground(theDisp,theGC,fcol);
lastpix = def.pixel = pix;
! XQueryColor(theDisp, theCmap, &def);
! sprintf(tmpstr, "Pix %3ld = ($%04x, $%04x, $%04x)",
! pix, def.red, def.green, def.blue);
! /* make the hex uppercase */
! for (sp=tmpstr+4; *sp; sp++)
! if (islower(*sp)) *sp = toupper(*sp);
XDrawImageString(theDisp,mainW,theGC,5,pvaly+10,tmpstr,strlen(tmpstr));
}
--- 361,378 ----
XSetForeground(theDisp,theGC,fcol);
lastpix = def.pixel = pix;
! if (pix<dispcells) {
! XQueryColor(theDisp, theCmap, &def);
! sprintf(tmpstr, "Pix %3ld = ($%04x, $%04x, $%04x)",
! pix, def.red, def.green, def.blue);
! /* make the hex uppercase */
! for (sp=tmpstr+4; *sp; sp++)
! if (islower(*sp)) *sp = toupper(*sp);
! }
! else {
! sprintf(tmpstr, "Pix %3ld is out of legal range. ", pix);
! }
XDrawImageString(theDisp,mainW,theGC,5,pvaly+10,tmpstr,strlen(tmpstr));
}
--
Mike Wexler(wyse!mikew) Phone: (408)433-1000 x1330
Moderator of comp.sources.x